Production of benzanthrones



Patented Mar. 17, 1936 iJNl'l'E S'i'ATEfi PATENT PRODUCTION OF BENZANTHRONES No- Drawing. Application January 23, 1933, Serial No. 653,218. Renewed January 16, 1935 19 Claims.

This invention relates to compounds of the benzanthrone series, more particularly benzanthrone itself, and a process for the production thereof.

It is known that by the condensation of benzene and phthalic anhydride in the presence of aluminum chloride, that is, by the Friedel-Craft synthesis, ortho-benzoyl benzoic acid is produced and this, on dehydration, yields anthraquinone. Also, various substituted anthraquinones are possible by the use of the Friedel-Craft synthesis. It is likewise known that benzanthrone or derivatives thereof may be produced from anthraquinone and its derivatives. Heretoiore, it has been customary to isolate the synthetic anthraquinone prior to its condensation to benzanthrone. Considering ortho-benzoyl benzoic acid as the starting material, this method of procedure represents a two-step process; namely, (1) the production of anthraquinone from ortho-benzoyl benzoic acid, and (2) the production of benzanthrone from the synthesized anthraquinone. This type of process has the disadvantage that it requires a relatively large consumption of raw materials, for example, sulfuric acid, in the separate steps and entails considerable labor and expense as well as loss of materials in the isolation of the anthraquinone.

It is an object of this invention to produce compounds of the benzanthrone series by a single step process. A further object is the production of compounds of the benzanthrone series directly from ortho-benzoyl benzoic acid and derivatives thereof. A still further object is the provision of a new and improved process for the production of compounds of the benzanthrone series which enables considerable savings in raw materials and labor over a prior art process of the character previously described. A more specific object is the provision of a new and improved process for the production of benzanthrone. Other objects will appear hereinafter.

These objects are accomplished according to the present invention whereby compounds of the benzanthrone series are produced in a single step process by reacting ortho-benzoyl benzoic acid or a derivative thereof with a ring closing agent, preferably of the sulfuric acid type, and subsequently, without isolating an intermediate product, subjecting the entire reaction mixture to treatment with a reducing agent and condensation with glycerine or a derivative thereof. It has been found that by this method of procedure that, contrary to expectation, a benzanthrone of good purity may be recovered in high yield.

While the invention is susceptible to considerable variation and modification in the manner of its practical application, particularly as regards the kind and proportions of the raw materials and the conditions of reaction, the following examples, in which the parts are by weight, will serve to illustrate how the invention may be practiced.

Example I Add 226 parts of ortho-benzoyl benzoic acid to 1630 parts of 8% to 10% oleum. Heat the charge, while agitating, to C. to C. until the ring closure to anthraquinone is complete, which usually requires about one hour. At the completion of the anthraquinone formation, cool the charge somewhat and dilute slowly with approximately 350 parts of water to an acid strength of 82% to 83%. At the end of the dilution adjust the temperature to 112 C. to 115C. Over the course of three hours add 160 parts of glycerine and 80 parts of finely ground iron at a uniform rate, holding the temperature at 112 C. to 115 C. Add about 12 parts of this glycerine before adding any iron. At the end of the addition of iron and glycerine heat the charge to C. and hold until the reduction and condensation are complete, which usually requires about three hours. Drown the charge in water and isolate the crude benzanthrone by filtering and then Wash acid-free with water. Remove the alkali soluble material from this crude benzanthrone by digesting in hot 1% caustic soda solution followed by a filtration and washing with water.

Erdmple II Dissolve 226 parts of ortho-benzoyl benzoic acid in 3000 parts of 5% oleum and heat to 100 C. to 105 C. until the ring closure has taken place and the formation of anthraquinone is complete. Cool the charge to 40 C. and add 240 parts of water to cut the acid strength to 93% to 95%. Over the course of one and one-half hours, add parts of copper powder at 40 C. and, after the addition of the same, hold three hours at 40 C. to 42 C. for the completion of the reduction. This copper powder is obtained by precipitating cop-per from copper sulfate solution by the addition of zinc dust.

Over the course of one hour add a solution of 2'17 parts of glycerine and 310 parts of water, allowing the temperature to rise to 40 C. The water thus added will dilute the acid to approximately 85% strength. After the addition of the glycerine and water, heat the charge very gradually over about one and one-half hours to 120 C. and hold it until the condensation is complete, which usually requires about three hours. Cool the charge to 60 C. and drown in water, isolating and purifying the benzanthrone as in Example I.

Example III Dissolve 240 parts of p'-methyl-o-benzoyl benzoic acid in 1740 parts of 5% oleum, and heat gradually to 105 C. to 110 C. until the ring closure has taken place and the formation of the b-methyl-anthraquinone is complete. Add approximately 365 parts of water at such a rate that the temperature does not exceed 110 C. This addition of water should dilute the acid to about 83% strength. Adjust the temperature to 112 C. to 115 C. and add 12 parts of glycerine. Add the balance of the glycerine and finely ground iron at a uniform rate over the course of three hours, using a total of 171 parts of glycerine and 85 parts of iron. Hold the charge at 115 C. to 118 C. for three hours to complete the reduction and condensation. Cool the charge to C. and drown in about 3500 parts of water at 60 C. Isolate the methyl-benzanthrone by filtering and washing acid-free with water.

Example IV Dissolve 260.5 parts of p-chloro-o-benzoyl benzoic acid in 1740 parts of 5% oleum and heat gradually to 105 C. to 110 C. until the ring closure has taken place and the formation of the 2-chloranthraquinone is complete. Add approximately 365 parts of water at such a rate that the temperature does not exceed 110 C. This addition of water should dilute the acid to about 83% strength. Adjust the temperature to 112 C. to 115 C. and add 12 parts of glycerine. Add the balance of the glycerine and finely ground iron at a uniform rate over the course of three hours, using a total of 171 parts of glycerine and 85 parts of iron. Hold the charge at 115 C. to 118 C. for three hours to complete the reduction and condensation. Cool the charge to 80 C. and drown in about 3500 parts of water at 60 C. The various chlor-benzanthrone isomers may be isolated in any suitable manner, for example, by filtering and washing acid-free with water.

Example V Add 340 parts of benz-chloro-p-phenyl-o-benzoyl benzoic acid (obtained by condensing p-chlor0 diphenyl with phthalic anhydride and AlCla) to 3000 parts of 5% oleum and heat to C. to C. until the ring closure has taken place and the formation of the chloro-phenyl-anthraquinone has gone to completion. Cool the charge to approximately 40 C. and add 625 parts of water. At the end of the dilution adjust the temperature to 112 C. to 115 C., then over the course of three to four hours add 125 parts of glycerine and 65 parts of iron at a uniform rate, maintaining the temperature at 112 C. to 115 C. After the glycerine and the iron have been added heat the charge to 118 C. to 120 C. and hold until the reduction and condensation are completed. Drown the charge in water and subsequently isolate the crude mixture of isomeric benz-chloro-beta-phenyl-benzanthrones by filtering and washing acid-free with water. The alkali soluble material from the mixture of benzanthrones may be removed by degisting the press cake in hot 1% caustic soda solution, followed by filtration and washing. In place of caustic soda, sodium carbonate may be employed.

The invention is generally applicable to the production of compounds of the benzanthrone series from ortho-benzoyl benzoic acids of the character described. As further specific examples of ortho-benzoyl benzoic acids which may be used in accordance with the invention may be mention in addition to those given in the examples: pethyl-o-benzoyl benzoic acid, p'-fiuoroo-benzoyl benzoic acid, chloro-methyl-o-benzoyl benzoic acids (obtained by condensing o-chloro-toluene or p-chloro-toluene with phthalic anhydride and aluminum chloride), the condensation products (Friedel-Craft) of phthalic anhydride, or monoor di-halogenated phthalic anhydrides with hydrocarbons such as benzene, naphthalene, anthracence, or substituted derivatives such as o, m and p xylene, isomeric dichloroand dibromobenzenes, anisole and the like. In Example IV the phenyl substituent of the p-phenyl-o-ben zoyl benzoic acid may carry instead of or in addition to chlorine, bromine, or hydroxyl groups. No matter what analogue or homologue may be chosen for conversion to compounds of the benzanthrone series, the general procedure outlined above will remain substantially the same.

As previously indicated, the ring closure or cyclization of the benzoyl benzoic acid is preferably carried out by means of a strongly dehydrating agent of the sulfuric acid type. The particular ring closing agent used may vary with the specific benzoyl benzoic acid treated. Good results have been obtained in the use of 100% sulfuric acid and 5% to 10% oleum.

The temperature employed in the cyclization of the benzoyl benzoic acid may vary within relatively wide limits, depending largely upon the ring closing agent used. Generally speaking, the reaction is preferably effected at the minimum temperature at which ring closure is completed. If the temperatures are too high, sulfonation may occur. Temperatures of about 100 C. to 120 C. have given good results.

After the cyclization of the benzoyl benzoic acid has been effected as indicated by the examples, the reaction mixture is preferably diluted with water. The concentration of the diluted mixture may vary within relatively wide limits but, as a general rule, should preferably not greatly exceed 95% H2504. During the condensation with glycerine, the concentration should preferably be about 80 to 85% H2804.

The reducing agent, preferably added to the diluted reaction mixture, may be any reducing agent well known in the art. For this purpose, it is generally preferable to use nascent hydrogen, such as may be obtained, for example, by the reaction of a metal (e. g., copper, iron, or aluminum powder) with the sulfuric acid. Other reducing agents common in the art, as, for example, aniline or aniline sulfate, may be used.

The temperature during the reaction may vary widely. When the reduction is carried out prior to condensation with glycerine, it is preferable to reduce at relatively low temperatures, say about 40 C. However, when simultaneous reduction and condensation methods are empl y higher peratures are preferably used, say 110 C. to 115 C., and finish at 120 C. D

The glycerine may be added to the reaction IIllX- ture before, during or after the addition of the reducing agent. In concentrated sulfuric acid, de-

hydration of the glycerine to acrolein occurs. Hence, a part or all of the added glycerine may be replaced by acrolein. If substituted benzanthrones (that is, substituted in the bz-ring) are desired, other glycerine derivatives, as for example, methyl acrolein, may be used. According to our preferred procedure, the glycerine or derivative thereof is added to the reaction zone simultaneously with the reducing agent. The conditions of reaction, such as temperature, may be those used in the art for the specific reactants employed.

The yields of benzanthrone obtained according to the present invention are high, being usually about to That a process of the char acter described could be carried out effectively without isolation of an intermediate product and yet obtain high yields could not be foreseen. When o-benzyl benzoic acid is similarly subjected to a cyclization treatment with sulfuric acid and condensed with glycerine without isolation of an intermediate product, benzanthrone may be obtained, but only in yields of about 15% to 20%.

An advantage of the invention is the saving in labor and material which is obtained by the use of a single step process as compared with a two-step process. In carrying out a two-step process, the consumption of sulfuric acid is double that re quired in a one-step process. The amount of iabor necessary to isolate an intermediate product such as anthraquinone and then finally recover benzanthrone in the two-step process is, of course, practically twice as much as that required for the isolation of benzanthrone alone in the single step process. The intermediate isolation in the two-step process also causes losses of materials, which are not incurred in the single step process. The one-step process also has the advantage in the use of less equipment, thereby reducing the capital expenditure for the plant. This includes drying, which the one-step process has reduced to half.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in the following claims.

We claim:

1. The process of producing a compound of the benzanthrone series which comprises subjecting an ortho-aroyl benzoic acid having free ortho-positions in the aroyl nucleus to treatment with a ring closing agent and subsequently subjecting the resultant reaction mixture to treatment with a reducing agent and condensation with glycerine or a derivative thereof.

2. The process of claim 1 in which the orthoaroyl benzoic acid is a compound obtainable by the condensation of a phthalic anhydride with a aryl hydrocarbon in the presence of aluminum chloride.

3. The process of claim 1 in which the orthoaroyl benzoic acid is a compound obtainable by the condensation of a halogenated phthalic anhydride with an aryl hydrocarbon in the presence of aluminum chloride.

4. The process of claim 1 in which the orthoaroyl benzoic acid is a compound obtainable by the condensation of phthalic anhydride with a halogenated aryl hydrocarbon in the presence of aluminum chloride.

5. The process of claim 1 in which the orthoaroyl benzoic acid is a compound obtainable by the condensation of phthalic anhydride with a compound of the benzene series in the presence of aluminum chloride.

6. The process of producing a compound of the benzanthrone series which comprises subjecting an ortho-benzoyl benzoic acid having free orthopositions in the benzoyl nucleus to treatment with a ring closing agent and subsequently subjecting the resultant reaction mixture to treatment with a reducing agent and condensation with glycerine or a derivative thereof.

7. The process of producing a compound of the benzanthrone series which comprises subjecting an ortho-aroyl benzoic acid having free orthopositions in the aroyl nucleus to treatment with a sulfuric acid ring closing agent and subsequently, without isolating an intermediate product, subjecting the resultant reaction mixture to treatment with a reducing agent and condensation vith glycerine.

8. The process of producing a compound of the benzanthrone series which comprises subjecting an ortho-benzoyl benzoic acid having free orthopositions in the benzoyl nucleus to treatment with a sulfuric acid ring closing agent and subsequently, without isolating an intermediate product, subjecting the resultant reaction mixture to treatment with a reducing agent and condensation with glycerine.

9. The process of producing a compound of the benzanthrone series which comprises subjecting an ortho-aroyl benzoic acid having free orthopositions in the aroyl nucleus to treatment with a ring closing agent and subsequently subjecting the resultant reaction mixture to simultaneous treatment with a reducing agent and condensation with glycerine.

10. The process of producing benzanthrone which comprises subjecting ortho-benzoyl benzoic acid to treatment with a sulfuric acid ring closing agent, and subsequently, without isolating an intermediate product, subjecting the resultant reaction mixture to treatment with a reducing agent and condensation with glycerine.

11. The process of producing benzanthrone which comprises heating ortho-benzoyl benzoic acid with about 5% to about 10% oleum at a temperature of about C. to about 120 C. until cyclization of the benzoyl benzoic acid is substantially complete, and subsequently diluting the resultant reaction mixture with water and adding theretoa reducing agent, then adding glycerine while maintaining a condensation temperature, and recovering the formed benzanthrone.

12. The process of producing benzanthrone which comprises heating ortho-benzoyl benzoic acid with about 5% to about 10% oleum at a temperature of about 100 C. to about 120 C., adding water to the reaction product in such amount that the sulfuric acid concentration is reduced to below 95%, adding to the diluted reaction mixture a metal capable of forming hydrogen by reaction with the sulfuric acid while maintaining a temperature of about 40 C., subsequently adding glycerine to the reaction mixture while maintaining a temperature of about C. to C., .and isolating the formed benzanthrone.

13. The process of producing benzanthrone which comprises heating ortho-benzoyl benzoic acid with about 5% to about 10% oleum at a temperature of about 100 C. to about 120 C. until cyclization of the benzoyl benzoic acid is substantially complete, subsequently diluting the resultant reaction mixture with water, and adding thereto simultaneously a reducing agent and glyc- 7 er'me, while maintaining a condensation temperature.

14. The process of producing benzanthrone which comprises heating ortho-benzoyl benzoic acid with about 5% to about 10% oleum at a temperature of about 100 C. to about 120 C. until cyclization of the benzoyl benzoic acid is substantially complete, subsequently diluting the resultant reaction mixture with water until the sulfuric acid concentration is about 80 to 85% and adding thereto simultaneously a reducing agent and glycerine, while maintaining a condensation temperature.

15. In a process of producing a compound of the benzanthrone series by subjecting an orthoaroyl-benzoic acid having free ortho-positions in the aroyl nucleus to treatment with a ring-closing agent and subsequently subjecting the resulting reaction mixture to treatment with a reducing agent and condensation with glycerine or a derivative thereof, the step which comprises adding a part of the glycerine or derivative thereof prior to the addition of the reducing agent.

16. In a process of producing a compound of the benzanthrone series by subjecting an orthoaroyl-benzoic acid having free ortho-positions in the aroyl nucleus to treatment with a sulfuric acid ring-closing agent and subsequently subjecting the resulting reaction mixture to treatment with a reducing agent and condensation with glycerine, the step whioh comprises adding a part of the glycerine prior to the addition of the reducing agent.

1'7. In a process of producing a compound of the benzanthrone series by subjecting an orthoaroyl-benzoic acid having free ortho-positions in the aroyl nucleus to treatment with a sulfuric acid ring-closing agent and subsequently subjecting the resulting reaction mixture to treatment with iron and glycerine, the step which comprises adding a part of the glycerine prior to the addition of the iron.

18. Compounds of the be'nzanthrone series containing fluorine in the anthrone nucleus, being identical with compounds obtainable by subjecting a fiuoro-ortho-aroy1-benzoic acid having free ortho-positions in the aroyl nucleus to treatment with a ring-closing agent, subsequently subjecting the resultant reaction mixture to treatment with a reducing agent and condensation with glycerine, and recovering the products.

19. A fluoro-benzanthrone containing fluorine in the anthrone nucleus being identical with the compound obtainable by subjecting para'-fluorobenzoyl-ortho-benzoic acid to treatment with a sulfuric acid ring-closing agent, subsequently subjecting the resultant reaction mixture to treatment with iron as a reducing agent and condensation with glycerin, and isolating the product.

FERDINAND W. PECK. JOHN H. SACHS. 

